Bobbin case opener mechanism for sewing machines



W. MAYERAN Sept. 13, 1960 ,BOBBIN CASE OPENER MECHANISM FOR SEWING MACHINES Filed April 4, 1958 INVENTOR. William Mayeran WITNESS :2

v 'TORNEY United States onc 2,952,229 BOBBIN SEWING MACHINES William Mayeran, Fair-field,- 'Conn:,.;assignor to .i The Singer Manufacturing Company,- -Elizabeth NJ]; a

corporation of New Jersey Filed Apr. 4,- 1958,8121; N6. 716,272

scams.- c1; 112-231 This invention relates to mechanism for opening a gap for the passage of the needle thread'btween the nonrotatirig bobbin case of a "rotary" 06k and the-rotation restraining means for the bobbin base; I It is an'object' of this invention'to' provide an improved bobbin case opener mechanism for a sewing machine liaving'a work support-ingpost;

Another object of this invention is to "provide a bobbin case opening mechanism 'for'a post-type sewing 'iriachin'e in which the timing of thebobbin case bpe'nir'ig may be changed by means acbessible from externally of the post without distiirb'ingor otherwise'advefsely affecting any other mechanis'rn' carried in the PdS t; I Withthe above and other objectsuand advantages in view as will hereinafter appear, a preferred 'form'of this invention is described hereinbelow and illustrated in the accompanyingdfawings'in'which:

Fig. 1 represents a top plan view of a sewing machine work supporting post having a bobbin case opening mechanism ofthis invention-applied 'tli'ereto; Fig. 2- represents a vertical cross-sectional view-6r the upper portion of the work supporting post takeii' substantially along-line -2-=2 of Fig;- 1; and

Pig. 3' represents a horizontal cross sectionahview taln substantially along line 3-3 of Fig. 2, with the hook driving shaft and bushing omitted.

In the drawings, 11 indicates the upper extremity ofa sewing machine work supporting post, post-type sewing machines being well known in the art for stitching operations on tubular or cupped articles such as shoes, gloves, etc., where manipulation of the work about the stitching point would be otherwise impractical.

Iournaled vertically in the work supporting post 11 in a bushing 12 secured by a set screw 13 in the upper extremity of the post is a hook drive shaft 14 formed with a bore 15 in which is secured a plug 16 which is axially threaded and formed with a transverse slot 18. Indicated at 19 is a rotary hook formed with a depending stud shaft 20 slabbed, as at 21, at its lower extremity to enter the slot 18 and drilled axially to accommodate a screw 22 threaded into the plug 16 to secure the hook for rotation with the hook shaft.

The hook 19 may be of any conventional construction within that known class of loop-takers which operates by virtue of a loop-seizing beak 23 to seize and carry a loop of needle thread about an under or bobbin thread mass preferably wound on a bobbin and contained within a bobbin case 24 journaled the hook 19. The bobbin case 24 is held in the hook by a gib 25 and is formed with a rotation restraining finger 26 which extends between bifurcated stop lugs 27 and 28 formed on a throat plate 29 secured by screws 30 to the post 11.

In operation, the hook illustrated in the drawings, rotating in the direction of the arrow in Fig. l, seizes a loop of needle thread from a needle (not shown) which descends through a needle aperture 31 in the throat plate. The seized loop of needle thread is then 2 a drawn out by the hook beak, the entire seized loop being initially beneath the level of the bobbin case rotation "restraining means 26, 27. and 28. That limb of. the needle thread loop' which originally is on the outside bf the hook beak is deflected upwardly andover th'e bobbin case 24 while that limb 'of the'needle thread which is originally on the inside of the hook beak is directed beneath'the bobbin case and the loop, or more accurately, each limb of the loop successively must sooner or later pass between the rotation restraining finger 26 and thestop lugs 27 and 28. Preferably to augment the natural mo= tions of the needle thread loop in being drawn around the bobbin case by the hook beak, the limb ofneedle thread loop which is originally outside the hook'beak should pass between thefinger 26 and the stop lugw27 as that limb is firstdrawri upwardly overthe bobbin case. Later as the thread loop: is bingdrawnofl the hook beak, the limb of needle thread which "has passed beneath the bobbin case should passbetween thefinger 2'6 and the stop lug 28'.- T-

The frictional drag of the rotating hobk on th'enorrrotafy bobbin cas journaled therein carries the rot-1r- -tion restraining finger 26 tightly against the stop 'lug 27. A considerable strain would/be placed upon thethread in being drawn between these parts but for the provision of what is referred to in the art as. a bobbin case opener. This opener. inechanism' opens a gap between the rotation restraining" finger of a bobbin case and that stopwlug against which the -restraining finger is urged by theft-ictional drag of the hook.' f

The bobbin case opener of this invention comprises a log 40'formed 'on the bobbin aseand an openeryfiiiger '41; which'extends upwardly from a 'plate 42, disposed beneath a guard disk 43 located directly under thehook 19. The plate 42 is formed with a circular aperture 4; which embraces an eccentric '45 fast on the stud shaft 20 of the book so that an orbital movement of the plate 42 and the" opener fingr41 will be derived from the rdta'tion' of the hook: The plate 42 is slotted, as. at -t6, substantially radially of the circular aperture 44' to embrace a slide block 47 pivotally supported in a slide block between the bushing and the slide block base. The under side of the slide block base is formed with an arcuate slot 50 opening into the clearance aperture 49. The outside edge 51 of the slide block base opposite the slot 50 is also made arcuate with the same center of curvature as that of the slot 50, to define an arcuate rib 52 depending from the slide of block base.

Fixed vertically in the post outwardly of the bushing 12 are two pins 53 which project upwardly and into the slot 50. The two pins 53 and the bushing 12 in contact with the small segment 49' of the aperture 49 in the slide block base provide a three-point support constraining the slide block base for turning movement about an axis substantially coaxial with that of the hook shaft so that the position of the slide block 47 may be changed to adjust the orbit and thereby the timing of the opener finger 41 into and out of engagement with the bobbin case lug 40.

The slide block base 48 may be locked in selected position by means of a pair of set screws 54 threaded radially through the post and bearing against the areaate outside surface 51 of the rib 52 on the slide block base. The set screws, as illustated in Fig. 3, are preferably disposed one opposite eachof the pins 53. When the set screws 54 are tightened, the slide block base is clamped against the pins 52 and the small segment 49' of the aperture 49 in the slide block base will be urged out of contact with the bushing 12. Thus, the slide block base will be completely free of the bushing and no bushing deformation or consequent binding of the hook shaft can possibly. occur.

The opener mechanism, operated by the eccentric 45 directly on the hook, will be given one cycle of oscillation for each rotation of the hook. As illustrated in Fig. l, the opener mechanism is preferably adjusted by means of the position of the eccentric 45 and the adjustment of the slide block base 48, so that the opener finger 41 will engage the bobbin case lug 40 to open a gap between the rotation restraining finger 26 and the stop lug 27 shortly after loop seizure by the hook beak 23. As the outer limb of the needle thread loop is carried upwardly over the bobbin case, an open path between the rotation restraining means will be provided for the outer thread limb to pass throug The opener finger 41 then moves away from the bobbin case lug 40 and the frictional resistance of the rotating hook on the non-rotating bobbin case will carry the rotation restraining finger 26 against the stop lug 27, opening a gap between the finger 26 and the stop lug 28 so that as the inner thread limb is withdrawn from beneath the bobbin case, an open path is provided for it between both the opener finger -41 and the lug 40 and between the bobbin rotation restraining means 26 and 28.

Having thus set forth the nature of this invention, what I claim herein is:

1. In a sewing machine having a work supporting post, a shaft bushing carried at one extremity of said post, a hook drive shaft journaled in saidbushing, a hook carried by said hook drive shaft for rotation in one direction, a non-rotary bobbin case, means for journaling said bobbin case in said hook, and interengaging bobbin case rotation restraining means on said post and on said bobbin case, bobbin case opener mechanism for periodically opening a gap between said bobbin case rotation restraining means, comprising a lug formed on said bobbin case, an opener finger, a plate supporting said opener finger and underlying said rotary hook, said plate formed with a circular opening, an eccentric carried for prises a pair rotation with said hook and disposed within said circular opening to impart orbital motion to said opener finger, means for constraining said opener finger to move into. and out of engagement with said bobbin case lug including a slide block, said plate formed with a slot disposed substantially radially of said circular opening and embracing said slide block, a slide block base formed with a clearance aperture loosely embracing said hook shaft bushing, means pivoting said slide block to said slide block base, interengaging guide means on said slide block base and on said work supporting post spaced from said hook shaft bushing for supporting said slide block base for turning movement coaxially of said hook drive shaft, and clamp means carried by said work supporting post for frictionally locking said interengaging guide means in selected angular position of said slide block base with respect to said work supporting post.

2. A bobbin case opener mechanism as set forth in claim 1 in which said interengaging guide means comof circular pins set in said work supporting post, each pin having an axis parallel to and equidistant from the axis of said hook drive shaft, said slide block base being formed with an annular slot embracing said P1118.

3. A bobbin case opener mechanism as set forth in claim 1 in which said interengaging guide means comprises a pair of circular pins set in said work supporting post, each pin having an axis parallel to and equidistant from the axis of said hook drive shaft, an annular rib depending from said slide block base at one side of said pins, and at least one set screw threaded radially into said work supporting post and bearing against the other side of said annular rib to lock said slide block base in place on said work supporting post.

References Cited in the'file of this patent UNITED STATES PATENTS 1,181,160 Parkes May 2, 1916 1,235,793 Gray Aug. 7, 1917 1,691,242 Greenwood Nov. 13, 1928 2,134,652 Christensen et al. Oct. 25, 1938 2,250,616 Zonis July 29, 1941 

